While for the most part it’s really good to see all this information in one place, I have to take issue with one part of “3. Improve your type” where the idea of using points is supported. I have found, when others do this, that it’s very frustrating when the end user (me, for instance) wants to print the item and the author/designer has used a type/size I have trouble reading. CSS-styled Points are not resizable in print or print-preview. A web document is still an electronic document until it hits the page, and should be sized in percentages/ems or anything resizable until it is a printed document, regardless of style sheet while it is still electronic.

To extend on what you’ve said here in part 2 & not using background images for branding; something I’ve done in the past when working on a site with a very dark background is put the on-white/print version of the logo in the HTML wrapped in a div, then using CSS hidden the image and used the on-black/website logo as the background image of the div.
Then, when looking at the print stylesheet you have a good logo to work with.

Obviously, universal PNG support would for the most part make this technique redundant.